/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.pinot.core.operator;

import java.util.Map;
import javax.annotation.Nullable;
import org.apache.pinot.core.operator.blocks.DocIdSetBlock;
import org.apache.pinot.segment.spi.datasource.DataSource;


public class ProjectionOperatorUtils {
  private static Implementation _instance = new DefaultImplementation();

  private ProjectionOperatorUtils() {
  }

  public static void setImplementation(Implementation newImplementation) {
    _instance = newImplementation;
  }

  public static ProjectionOperator getProjectionOperator(Map<String, DataSource> dataSourceMap,
      @Nullable BaseOperator<DocIdSetBlock> docIdSetOperator) {
    return _instance.getProjectionOperator(dataSourceMap, docIdSetOperator);
  }

  public interface Implementation {
    /**
     * Returns the projection operator
     */
    ProjectionOperator getProjectionOperator(Map<String, DataSource> dataSourceMap,
        @Nullable BaseOperator<DocIdSetBlock> docIdSetOperator);
  }

  public static class DefaultImplementation implements Implementation {
    @Override
    public ProjectionOperator getProjectionOperator(Map<String, DataSource> dataSourceMap,
        @Nullable BaseOperator<DocIdSetBlock> docIdSetOperator) {
      return new ProjectionOperator(dataSourceMap, docIdSetOperator);
    }
  }
}
